Dr. SilvaUs laboratory studies aspects of the pathogenesis and epidemiology of C. difficile infection. Though the primary emphasis is in humans, Dr. Silva is also interested in the role of C. difficile in diarrhea or other intestinal diseases in different animals. His laboratory has at present a collaborative research project with the UCD Veterinary Teaching Hospital which includes the study of dogs, cats and horses. We have found a significant correlation between the presence of C. difficile and diarrhea in horses. Dr. SilvaUs laboratory in involved in developing a molecular typing scheme for C. difficile. We compare isolates from the environment and from different animals in attempts to better define the epidemiology of this pathogen. In early 1995, ten stool specimens from monkeys were submitted to Dr. SilvaUs laboratory for determining the presence of C. difficile. These specimens were cultured on selective medium for bacteria. In addition, Dna was extracted from the speciments and PCR was performed to detect the presence of C. difficile toxins. We found all the specimens to be negative for these tests.